MAX8770GTL+T Maxim Integrated Products, MAX8770GTL+T Datasheet - Page 23

• Manufacturer Part Number: MAX8770GTL+T
• Description: IC CTLR PS 2/1PH QUICK PWM 40QFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8770GTL+T

• Applications: Controller, Intel IMVP-6
• Voltage - Input: 4 ~ 26 V
• Number Of Outputs: 1
• Voltage - Output: 0.125 ~ 1.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PWM Controller for IMVP-6+ CPU Core Power Supplies
minimize the current-sense error due to the current-
sense inputs’ bias current (I
R1||R2 to be less than 2kΩ and use the above equation
to determine the sense capacitance (C
capacitors with 5% tolerance and resistors with 1% tol-
erance specifications. Temperature compensation is
recommended for this current-sense method. See the
Voltage Positioning and the Loop Compensation sec-
tion for detailed information.
When using a current-sense resistor for accurate out-
put-voltage positioning, the circuit requires a differential
RC filter to eliminate the AC voltage step cause by the
equivalent series inductance (L
sense resistor (see Figure 3). The ESL-induced voltage
step does not affect the average current-sense voltage,
CONFIDENTIAL INFORMATION – RESTRICTED TO INTEL
Figure 3. Current-Sense Methods
MAX8770/MAX8771/MAX8772 Dual-Phase, Quick-
______________________________________________________________________________________
A) OUTPUT SERIES RESISTOR SENSING
B) LOSSLESS INDUCTOR SENSING
CSP
PGND
CSN_
PGND
CSN_
CSP_
CSP_
DH_
DH_
DL_
DL_
LX_
LX_
_ and I
ESL
) of the current-
N
N
N
N
H
H
L
L
CSN
EQ
_), choose
). Choose
D
C
D
C
L
IN
L
IN
L
R1
INDUCTOR
L
INPUT (V
INPUT (V
FOR THERMAL COMPENSATION:
R2 SHOULD CONSIST OF AN NTC RESISTOR IN
SERIES WITH A STANDARD THIN-FILM RESISTOR
but results in a significant peak current-sense voltage
error that results in unwanted offsets in the regulation
voltage and results in early current-limit detection.
Similar to the inductor DCR sensing method above, the
RC filter’s time constant should match the L/R time con-
stant formed by the current-sense resistor’s parasitic
inductance:
where L
current-sense resistor, R
tance value, and C
matching components.
L
SENSE RESISTOR
ESL
R1
DCR
C
R2
EQ
IN
IN
)
)
R
SENSE
ESL
C
EQ
is the equivalent series inductance of the
C
OUT
R
C
EQ
OUT
R
L
SENSE
®
R
DCR
ESL
CS
and R
=
=
IMVP-6 LICENSEES
(
C
SENSE
C
L
EQ
EQ
R1 + R2
[
R1 =
R2
=
R1 R2
1
C
EQ
+
L
R
EQ
)
SENSE
SENSE
1
R
is current-sense resis-
]
DCR
are the time-constant
R
1
23